Being expected to explain and justify your decisions is pretty reasonable, IMO.

Sure, but we who spend most of our time working on the "invisible" bits on the backend generally don't have the minutiae of our decisions subjected to a whole lot of scrutiny by the average client.

In contrast, the cliche is true: everyone thinks he is qualified to critique front end design.

I don't think this is always a bad thing -- certainly the client is the ultimate keeper of his brand, but I can appreciate that the constant second-guessing might get tiresome.

To the OP, all I can recommend is to choose your clients carefully, know them well enough to anticipate the issues, fire the ones that are incompatible, and become expert enough that their default instinct is to trust your judgement. Good luck.

Depends, if you have to justify every little thing there's a problem, it can go beyond the reasonable. Either they don't like your work, or they don't trust you, or both.

Yeah I've run into that quite a bit. "Tell me WHY you can't have 3 layers of tabs and a search bar across the top."

Answer: You hired me to design this, either trust me and get out of the way, or hire someone else.

You can explain a few things at first, but at some point they just have to trust you.